摘要
Al-Mg-Si-Cu铝合金(6XXX)属于可热处理强化合金,其高比强度、耐腐蚀及优良的成形性能使得它们在各种工业应用中具有吸引力,包括电力传输和交通运输行业;但相对较低的强度和硬度限制了其应用。最新研究表明,在合金中加入Mn/Cr等过渡族元素结合均匀化热处理工艺能够在Al-Mg-Si-Cu铝合金基体中形成纳米级、与基体部分共格的α-Al(MnCr)Si弥散相,从而借助弥散强化作用进一步提升合金的综合力学性能,拓展Al-Mg-Si-Cu铝合金的应用范围。弥散相因其对位错运动和(亚)晶界迁移的钉扎作用而有助于限制动态回复并抑制动态再结晶。此外,弥散相还能够限制合金在固溶处理过程中再结晶晶粒的形核和长大过程,进而抑制静态再结晶的发生。但较少有文献针对弥散相对Al-Mg-Si-Cu合金变形后热处理过程中的微观演变进行量化统计和机理分析,未能建立模型来描述变形条件对微观组织演变的影响。本工作对6061合金和Mn/Cr微合金化的Al-Mg-Si-Cu合金(后者被标记为HSW-1合金)在不同条件下进行热变形处理(变形温度:300、400、500℃;应变速率:0.01、0.1、1、10 s^(-1);真应变:1.2),研究变形合金在固溶和时效热处理过程中的微观结构演变,提出热变形合金经固溶处理后的微观组织调控机制。采用TEM观察证实了HSW-1合金基体中均匀分布着大量纳米级的α-Al(MnCr)Si弥散相。将热变形后的两种合金在560℃下盐浴保温不同时间,应用准原位EBSD技术表征微观结构的演变,统计取向差分布及亚晶粒尺寸的变化。结果表明,热变形条件(变形温度、应变速率)对6061和HSW-1合金在固溶处理过程中的静态再结晶行为有显著影响。两种合金静态再结晶行为随着变形温度的降低、应变量的增加及应变速率的升高而得到强化。相同的变形条件下,尽管6061合金静态软化驱动力低于HSW-1合金,但其在固溶处理过程中的静态再结晶行为明显强于HSW-1合金。这表明,弥散相通过钉扎作用有效抑制变形合金在固溶和时效过程中的静态再结晶行为,在显著提升合金的抗再结晶能力的同时保持变形合金的微观结构,使变形合金获得弥散强化和变形强化的综合效果,进而赋予其高强度。最后,通过理论分析提出了T6热处理后两种变形合金的微观结构控制模型。通过调整变形参数,即变形温度和应变速率,可以精确调节热处理后的微观组织成分,实验数据有效支持了模型的可行性。该结果为开发新型高强韧高性能铝合金提供了实验基础和理论分析。
In this work,the commercial 6061 alloy and a Mn/Cr micro-alloyed Al-Mg-Si-Cu(denoted as HSW-1 alloy)were subjected to thermal deformation treatment under different conditions(deformation temperature:300,400,500℃;strain rate:0.01,0.1,1,10 s^(-1);true strain:1.2)to study the microstructure evolution of the deformed alloys during solution and aging heat treatments.TEM observation confirmed that a large number of nano-scaleα-Al(MnCr)Si dispersiods were uniformly distributed in HSW-1 alloy.Then quasi-in-situ EBSD analysis was used to characterize the microstructure evolution and count the distribution of misorientation distribution as well as sub-grain size changes of the two deformed alloys during different soaking times at 560℃.The results showed that the dispersiods could significantly improve the recrystallization resistance of Al-Mg-Si-Cu alloy,maintain the deformation microstructure and obtain high-strength alloys.Finally,theoretical analysis was applied to propose a control model for the microstructure of the two deformed alloys after T6 heat treatment.The microstructure composition after heat treatment can be precisely regulated by adjusting the deformation parameters,that is,deformation temperature and strain rates,and the experimental data effectively support the feasibility of the model.
作者
王孝国
秦简
刘方镇
长海博文
WANG Xiaoguo;QIN Jian;LIU Fangzhen;NAGAUMI Hiromi(College of Agricultural Engineering,Shanxi Agricultural University,Taigu 030801,Shanxi,China;High Performance Metal Structural Materials Research Institute,Soochow University,Suzhou 215021,Jiangsu,China;Shagang School of Iron and Steel,Soochow University,Suzhou 215021,Jiangsu,China)
出处
《材料导报》
CSCD
北大核心
2023年第24期208-215,共8页
Materials Reports
基金
financially supported by National Natural Science Foundation of China(U1864209)
Shanxi Province Key Research and Development Plan Project(201903D211002)
Shanxi Agricultural University Doctorat(SXBYKY2021021,2020BQ80)。
